城市公园植被特征对陆生鸟类集团的影响

城市公共绿地是城市生态系统中重要的鸟类栖息地,其植被特征对鸟类集团存在显著影响。在通过分析植被特征对陆生鸟类集团的作用,从而为公园合理配置植被来提高其作为野生动物栖息地的生态服务功能提供理论基础。2009年10月至2011年10月,采用样线法对上海滨江森林公园进行鸟类调查,利用主成分分析划分鸟类集团,用高度定义植被层次,用卡方检验分析鸟类行为在植被层次上的差异。结果表明,滨江森林公园陆生鸟类群落在乔木层的栖息行为和运动行为频次显著多于其在灌木层和地被层的行为频次,在地被层的取食行为频次显著多于其在乔木层和灌木层的行为频次。陆生鸟类可划分为8个鸟类集团,鸟类集团之间存在栖息、运动和取食空间生态位的重叠。食虫拾取集团、杂食拾取集团、食肉飞取集团和植食拾取集团在栖息、运动和取食空间生态位上均存在较高的重叠度,其通过食性分离各自空间生态位。食虫探取集团和食虫飞取集团互为栖息空间生态位重叠度最高集团,其通过取食方式的不同来实现生态位的分离。根据公园植被特征对鸟类集团的影响结果对上海市公园绿地植被配置提出了建议。     

Seasonal dynamics of guild structure in a bird assemblage of the central Monte desert

Most studies of ecological guilds consider guild membership as a fixed attribute of species, and the guild structure as a fixed attribute of a community. Consequently, almost no study tackled the examination of temporal changes in the guild structure of a particular assemblage. We used data on foraging patterns of central Monte desert birds to assess seasonal differences in resource use by resident species, and to examine seasonal changes in the guild structure of the assemblage. From 1993 until 1999, we quantified the use of foraging substrates, manoeuvres, and height strata, and the utilisation of plants by 18 bird species. Resident species showed different kinds of seasonal dynamics, from no noticeable to drastic changes in their foraging patterns. Seasonal changes in guild structure were remarkable. Only two guilds were present all year round (ground foragers and foliage foragers), although they suffered important species turnover. Three other guilds had a seasonal occurrence: graminivores (during the non-breeding season), arboreal herbivores, and aerial feeders (during the breeding season). Two species changed from one guild to another between seasons. Both presence–absence of migrant species, and changes in the feeding ecology of resident species had an influence on the temporal dynamics of guild structure. These factors appeared to be related with changing resource availability, especially with the birds’ ability for facing lean conditions through migration and with the opportunistic use of seasonally superabundant resources. Our results undermine the trust in studies in which guild structure was assessed irrespective of temporal variations. We show also that guild membership is not a fixed attribute of a species: we should rather evaluate the individuals’ resource use in a given moment to assign them to a guild, instead of obtaining a single measure purporting to represent a species’ fixed attribute.     

Persistence of community structure: what happens when you change taxonomic scale?

It is common in community ecology to use the species as the taxonomic category of interest, yet in rich tropical assemblages containing guilds of very similar species this may not be appropriate. Such assemblages may be organized at the level of guilds rather than at the finer species level. In a ten-year study of assemblages of fish at One Tree Reef, Great Barrier Reef, we found species composition and the number of fish on a given lagoonal patch reef vary greatly across time (Sale and Douglas 1984; Sale et al. in preparation). The mean average proportional similarity of a reef's assemblage to itself at different times (censuses) is usually low at a value of around 0.5. This apparent variability may be ecologically irrelevant noise if organization is at the higher guild level. We have recast our database at the guild level to test this possibility. Thirteen guilds were defined by the diets, foraging habitats and times of the individual species comprising them. Similarity of an assemblage to itself at successive censuses was re-calculated using the number of individuals in each guild instead of the numbers in each species. This analysis yielded significantly higher levels of similarity (P<0.01) among censuses. To test whether this increase in similarity was due solely to the smaller number of categories used to calculate the similarity indices, 5 sets of randomly generated guilds were constructed using a Monte Carlo approach. No significant difference (P>0.05) was found between the average similarity among censuses when assemblages were classified into these null guilds and when they were classified according to the real guilds. These results indicate that shifting to the larger taxonomic scale of guilds does not reveal a significantly more persistent assemblage structure than that revealed when analysis is at the smaller scale of species. There is no evidence of an underlying organization of these assemblages at the guild level.     

云南哀牢山徐家坝常绿阔叶林的鸟类取食集团

2006年3-4月,采用无距离估计样线法对云南哀牢山徐家坝中山湿性常绿阔叶林中的鸟类群落做了直接观察,观察到鸟类取食行为14 345次只.运片j聚类分析,依据鸟类的栖息取食行为格局将62种鸟划分为11个取食集团:(G1)地面拾取集团、(G2)地面扒取集团、(G3)树冠层飞取/拾取集团、(G4)树冠层飞取集团、(G5)树干层探取集团、(G6)灌层竹秆探取集团、(G7)树干粗枝搜寻集团、(G8)树冠层粗枝搜寻集团、(G9)树冠层拾取集团、(G10)灌丛下层叶层/树干/地面拾取集团、(G11)灌层拾取集团.结果表明,由于各个集团在栖息基层、取食基层及取食方式上的分离,使各集团分割了该地区的取食空间和食物资源;而集团内部的各个种间主要通过对取食高度的划分,使得集团内部的取食空『白j和食物资源得到了更深层次的利用,使种间竞争减至最小.其结果还表明,鸟类取食集团的数量和结构因不同的植被类型而异,顶级群落中包含的鸟类种类更多,各个种间的生态位分化也更为细致.     

On the use of the guild concept in plant ecology

The original definition of the guild is reiterated and the concept discussed and placed in the context of related concepts such as resources and competition. From this conceptual framework the current use of guilds in studies of plant community ecology is evaluated. We discuss the criteria with which species are assigned to guilds, the association of guilds with specific communities, the resource classes on which guilds are based, and the competitive relationships between species of a guild. We conclude that the guild is presently applied in a much more loose way as compared to its original definition. In particular, the a priori assignment of species to guilds on the basis of the use of well-defined resource classes is often relaxed. This obscures the insight that the guild structure may provide in the role of resource partitioning and competition in structuring the community. A more strict use of the concept is advocated.     

The impact of cattle grazing regimes on tropical savanna bird assemblages

Globally, agricultural land use is implicated in the decline of avifauna. In rangelands (areas used for livestock grazing), bird community responses to grazing can be complex, species‐specific and scale dependent. A greater understanding of bird responses to grazing will lead to more meaningful management recommendations. We tested the hypothesis that foraging height predicts bird species’ responses to grazing, such that species using lower vegetation strata are most likely to respond to the impacts of livestock grazing. We examined the response of a tropical savanna bird community to four grazing strategies at a long‐term grazing trial in northern Australia. We predicted that ground‐foraging guilds would be more responsive to grazing treatment than foliage‐ or aerial‐foraging guilds. We analysed the bird community assemblage using generalised linear mixed models and examined individual species’ abundance in relation to microhabitat variables. We found that while ground‐foraging guilds were more responsive to grazing treatment, individual species dynamics within a foraging guild could be contradictory. For example, the red‐backed fairy‐wren decreased in abundance with increased grazing and was positively associated with grass and shrub (Carissa ovata) cover, whereas Australian magpies increased in abundance in the most heavily grazed paddocks. In general, the responses of bird species to grazing were more pronounced in guilds that forage closer to the ground, but whether the responses were positive or negative was driven by bird species ecology. Measures examining the responses of individual species are more useful than assemblage measures (such as richness) to describe the impacts of anthropogenic disturbance such as grazing.     

鼎湖山森林鸟类群落的集团结构

本文应用生态学中正在发展的集团理论,分析了鼎湖山季风常绿阔叶林繁殖季节鸟类群落的组成。该鸟类群落由28种鸟组成。根据鸟类的取食方法、取食基层和取食高度取定的取食行为格局,使用了聚类分析法和主分量分析法把这鸟类群落划分为8个不同的取食集团。由于集团内成员的取食行为格局十分相似,把群落划分为集团后,更有利于研究群落内种间的相互作用,也便于了解群落内资源分割的情况。文中讨论了划分鸟类集团的依据,并就集团理论及其应用作了探讨。     

大别山山地次生林鸟类群落集团结构的季节变化

2007年12月—2008年12月,在大别山鹞落坪,对落叶阔叶次生林鸟类的集团结构的季节变化特征进行了研究。采用连续取样法采集鸟类取食行为数据,用聚类分析法对繁殖和非繁殖季节鸟类群落进行集团划分,通过无倾向对应分析（DCA）对32种森林鸟类的两个季节资源利用特点进行了研究。结果表明,鸟类群落在非繁殖季节可以分为地面、灌丛、树干（枝）、冠层等4个取食集团,而在繁殖季节还出现空中取食集团;候鸟影响鹞落坪次生林鸟类群落取食集团的结构,产生新的取食集团。DCA的第一轴主要代表鸟类取食高度信息,第二轴主要代表鸟类取食位置信息,第三轴代表鸟类取食方式和取食基质信息;用DCA前两轴对32种鸟类排序表明,有6种鸟主要在第一轴发生变化,有4种鸟主要在第二轴发生变化。     

Bird Community Composition in a Shaded Coffee Agro-ecological Matrix in Puebla,Mexico: The Effects of Landscape Heterogeneity at Multiple Spatial Scales

This study examined the importance of habitat heterogeneity on the avian community composition, and investigated the scale at which species abundances respond to habitat variables. The study was conducted within a diverse landscape matrix of a shaded coffee region in Mexico. To detect at which characteristic spatial scale different species and foraging guilds respond most strongly we analyzed the effect of plot-, patch- and landscape-level variables at different spatial extent (i.e., different kilometer radii) on species composition and foraging guilds. We used redundancy analysis to identify species–environment correlations, and to identify predictor variables that best explained the bird community structure, quantified the influence of plot-, patch- and landscape-level variables on the bird community composition. In addition, we used the 4th-corner method to detect significant relationships between the dietary guilds and plot-, patch- and landscape-level variables. We recorded 12,335 individuals of 181 bird species; 105 bird species were recorded foraging within the shaded coffee plantations. We found that plot- and landscape-level variables significantly explained the bird community composition best across all scales, and were significantly correlated with the abundance of the dietary guilds. In contrast, patch-level variables were less important. Habitat composition variables (i.e., coffee, forest and agricultural area) were among the most important predictors. Canopy structure was more important than other vegetation structure variables in explaining dietary guild structure. Hence, the maintenance of a heterogeneous landscape with a high-quality matrix within an agro-ecological region enhances bird conservation.     

THE BIRD COMMUNITY OF TASMANIAN TEMPERATE RAINFOREST

The avifauna of Tasmanian temperate rainforest consists of 21 species, more than hitherto reported. Eleven species are very common, six are common and a further four species that have large home ranges are uncommon. Other species occur occasionally or accidentally.
The structure of the Tasmanian rainforest community was determined from measured overlaps in horizontal habitat selection, vegetation layer utilization and foraging site distribution. This demonstrates the existence of guilds, the members of which react more with each other than they do with members of other guilds. Niche differentiation is shown in each guild in the breeding season. However, adaptations enabling survival during the non-breeding season may be important in the seasonal Tasmanian environment.